The invention relates generally to devices for cutting a web of material as it is being wound onto a roll and, more particularly, to a device that slashes and tears the web to create a free end that is thereafter blown onto an empty core or spool so that the web material may be wound continuously.
Flexible sheet materials, such as paper, are often produced as continuous sheets or "webs" by lines of machinery. When a line of papermaking machinery is initially activated, such as at the beginning of a work shift, adjustments must be made before the resulting web of paper is of acceptable quality. These adjustments consume a considerable amount of time and effort. In addition, a significant amount of papermaking material is wasted as the adjustments are fine-tuned. As a result, it is desirable to run a papermaking line continuously once it is fully adjusted.
Paper webs are typically wound upon a roll at the end of the papermaking line for storage or to await further finishing work. As the web of paper is continuously drawn off of the end of the papermaking machine line and wound about the roll, the size of the roll will increase until it becomes necessary to begin a new roll. To avoid machinery readjustments and the disadvantages associated therewith, it is desirable to cut the paper web and feed the resulting free end onto an empty core or spool without stopping or slowing the papermaking line. Various devices and arrangements have been proposed to accomplish such a function.
Blades are frequently used to cut paper webs. These blades may have a length extending over the entire cross-machine width of the web, or, alternatively, a short knife may be used that is moved transversely across the width of the web. An example of the latter is the device disclosed in U.S. Pat. No. 3,365,992 to Dreher. Dreher shows a carriage assembly with a short knife pivotally mounted to its bottom and an adhesive sprayer positioned on its top. The carriage is mounted upon cross-machine spanning rails so that it may travel across the width of the web. This allows the knife to cut the web. As the knife is cutting the web, adhesive is sprayed upon an adjacent empty spool. As a result, the web is wound about the spool as the newly-cut portion contacts the sprayed adhesive.
While the device of Dreher is effective, it requires the use of adhesive to feed the web onto a spool. This is an additional material cost. Furthermore, the web is actually cut obliquely due to the web's continuous movement as the knife travels across it. This results in greater paper waste. The cross-web travel of the knife also limits the speed at which the device may be operated. An additional disadvantage to Dreher is that the knife blade must occasionally be sharpened. This translates into increased maintenance requirements. Features such as the moving carriage mechanism and the adhesive spray nozzles add to the bulkiness and complexity of the device and thus also increase maintenance and space requirements.
A device utilizing a cross-machine length blade is shown in U.S. Pat. No. 3,049,311 to Birch. The Birch device features a bottom-hinged curved grating mounted upon a hydraulic cylinder that is positioned beneath the exit side of a driving roller. The grating is elevated in a direction perpendicular to web travel when the hydraulic cylinder is activated. A cutting blade is positioned across the top of the grating so that the web is cut when the grating is elevated. A number of small rollers are positioned near the top of the grating so that the newly cut web is wrapped about a spool positioned above the driving roller as the grating is further elevated.
While this device overcomes the cost of using adhesive and does not produce as much waste as the device of Dreher, it is still mechanically complex and bulky. In addition, the cutting blade would require periodic sharpening. As a result, the device of Birch would also suffer from significant maintenance and space requirements. Furthermore, the bulk of the device would make high-speed operation difficult.
Devices have also been developed that utilize jets of air to lap a severed web onto an empty spool. An example of such a device is presented in U.S. Pat. No. 3,845,914 to Straujups. Straujups uses a chain-cutting mechanism that spans the width of the web. This mechanism is powered by an electric motor and cuts the web from below as it is elevated via a hydraulic cylinder. A series of air jets are positioned across the cutting mechanism. This allows the severed end of the web to be blown or "air lapped" onto a waiting spool as the mechanism is elevated beyond the cutting position.
While Straujups eliminates the additional material costs and some of the complexity of earlier lapping arrangements, the cutting mechanism is still bulky and mechanically complex. The cutting chain requires periodic sharpening and lubrication and the hydraulic cylinder has maintenance requirements. The electric motor powering the cutting chain would also consume energy and occasionally require servicing or replacement. The bulk of the cutting portion would once again make high-speed operation difficult.
Turnup blow pipes, or gooseneck turnups, have long been used in the paper manufacturing industry to lap the free end of a paper web about a spool. A primary advantage of turnup blow pipes is their compactness and simplicity. These devices typically consist of a pipe positioned in a primarily vertical orientation. The pipe features an opening at its top end and is connected to a source of pressurized air. The top portion of the pipe is angled slightly so that a stream of air travels through the opening in a direction tangential to the spool. Turnup blow pipes are typically oriented below the spool and downstream from the driving roller of the papermaking line.
While turnup blow pipes have proven to be an effective means of lapping paper about a spool, attempts to use the devices as cutters have been less successful. More specifically, the air streams produced by the devices have thus far been found to be suitable only for cutting and tearing very thin grades of paper. This is because a very high air pressure is required to initially burst through the web to start the tear. After this initial burst, however, a lower air pressure will suffice in completing the tear. Most turnup blow pipes do not provide sufficient air pressure to reliably perform the initial bursting function.
If a turnup blow pipe featured a device that would allow it to make a more direct or "positive" initial burst, that is, more of an initial mechanical slash, it could be used to cut thicker grades of paper, or other materials without the use of very high air pressure. Such a device would drastically increase the utility of turnup blow pipes.
Accordingly, it is an object of the present invention to provide a web cutting and lapping device that allows for continuous and high-speed operation of the web-producing machinery.
It is another object of the present invention to provide a web cutting and lapping device that does not utilize knives or blades.
It is another object of the present invention to provide a web cutting and lapping device that is relatively compact.
It is another object of the present invention to provide a web cutting and lapping device that possesses simple construction and low maintenance requirements.
It is still another object of the present invention to provide a web cutting and lapping device that does not use adhesives and that minimizes paper waste.
It is still another object of the present invention to provide a web cutting and lapping device that provides for a positive initial slashing of the web.
It is still another object of the present invention to provide a web cutting and lapping device that may incorporate existing turnup blow pipes.